Hydraulic drive mechanism for step-by-step conveyers



G. G. DRAGQ Dec. 23, 1952 HYDRAULIC DRIVE MECHANISM FOR STEP-BY-STEP CONVEYERS Filed July 16, 1949 2 SHEETS-SHEET 1 INVENTOR. 9 an aflcomo \Zffleo gni/f5 G. G. DRAGO HYDRAULIC DRIVE MECHANISM FOR STEP-BY-STEP CONVEYERS 2 SHEETS-SHEET 2 Filed July 16. 1949 INVENTOR. 6/0 Glace/n a .24 A0 0 Aye/2Z3 Patented Dec. 23, 1952 UNITED STATES ATENT GFFICE HYDRAULIC DRIVE MECHANISM FOR STEP-BY-STEP CONVEYERS Application July 16, 1949, Serial No. 105,226 In Italy July 17, 1948 2 Claims.

The present invention relates to a hydraulic drive system for step-by-step conveyors or the like, and more particularly for the conveyor floor of a kiln or drying tunnel.

It is known that the construction of drive systems for the conveyor floor of continuous drying kilns or tunnels is complicated by the fact that the parts must be constructed of durable and non-oxidizable metal. This limits the possibility of obtaining the higher temperatures at which the kilns operate more satisfactorily such as with electric heating elements.

In order to overcome this disadvantage stepby-step conveyors have been designed having one or more longitudinal movable elements placed in parallel and in series. These elements may be constructed of materials other than metal and they act as a shield for the metal parts which control their movements. It is customary to control the movements of such step-'bystep movable elements by mechanical means which are of complex and expensive construction, particularly where kilns of great length are involved.

The principal object of this invention is to provide a step-by-step conveyor of the type described wherein the movements are controlled by hydraulic means. It is known that hydraulic power can be transmitted to any required distance simply by extending a fluid pipe line, and this advantage enables the conveyor according to the present invention to be adapted to any length of kiln.

In one form of hydraulic drive system according to the present invention there are provided a series of means controlling the vertical movement of a plurality of horizontal longitudinally movable elements and means controlling longi tudinal movement thereof.

The vertical movement of the elements, which may be referred to as traveling beams, is obtained by a hydraulic servo-motor acting as a pilot to supply fluid to a plurality of vertically reciprocating pistons. This servo-motor is controlled by a slide valve actuated by a cam operated by a drive motor.

The longitudinal movements of the traveling beams are controlled also by a servo-motor to which the supply of fluid is controlled by a slide valve similarly actuated by a cam operated from the same drive motor.

The traveling beams forming the conveyor are supported and conveyed along the heads of the vertically reciprocating pistons by means of rollers cooperating with a system of guide rails or with an adjacent parallel traveling beam.

The 7 system further includes an hydraulic pump, preferably driven by the same motor as the above mentioned cams, and a system of sup: ply and discharge conduits from the pump to the slide valves, servo-motors and pistons and return or discharge conduits therefrom to a sump from which the pump draws fluid to supply it under pressure through the supply lines.

In the accompanying drawings Figures 1c; and lb illustrate diagrammatically a complete drive system in accordance with the invention and Figures 2-5 illustrate the movements of the traveling beams controlled by the system of Figure 1.

In Figure 1 there is shown a servo-motor comprising a, cylinder la having a piston lb slidable therein. The piston 'lb-is of the differential type having a circular face at the left hand side of larger surface than a second annular face at the right. The movements of the piston lb in the cylinder la are controlled by a slide valve 2a having a valve member 2b reciprocating therein. The movements of the valve member 2b are controlled on the one hand by a bell crank lever 3a and a linkage system 3b and by a cam llia acting on the linkage system 3b. The bell crank lever 3a i connected to a rod I i, the movements of which correspond to the movements of the piston lb and the operation of which will be described hereinafter.

In the position shown in the drawing, the valve member 2b closes the supply port of the slide valve 2a interrupting the supply of fluid under pressure to the left hand side of the cylinder la. Upon rotation of the cam Illa, the slide member 2b will be lifted by the linkage system 3b and fluid will be supplied to the cylinder la. Since the right side of the cylinder la is in permanent communication through conduits lEa with the supply side of a pump l3, and since the piston lb is of the differential type, the supply of fluid under pressure through the slide valve 2a to the left hand side of the cylinder la. will cause movement toward the right of the piston lb. Movement toward the right of the rod l4 with the piston lb will cause clockwise rotation of the bell crank lever 3a and lowering of the valve member 2b thereby interrupting the supply of fluid under pressure to the cylinder la.

At the same time the movement to the right of the rod l4 will cause counterclockwise rota-.- tion of each one of a series of hell crank levers 6a connected to the rod [4 at spaced points thereof. The rod l4 extends longitudinally throughout the length of the conveyor beneath which there are provided at spaced points a series of lifting motors 4 each comprising a cylinder 4a and a piston 4b reciprocating therein. The pistons 4b of the motors 4 are each connected by a linkage system 6b with the bell crank lever 6a and with the valve members 5b of a corresponding series of slide valves 5a controlling the supply of fluid under pressure to the cylinders 40.. Such counterclockwise movement of the bell crank levers 6a: will lower the valve members 5b from the position shown in the drawing to open the supply ports and deliver fluid under pressure to the lower end of the cylinders 4a from the supply conduit l6a, thus causing upward movement of the pistons 4b.

When the piston lb and rod l4 have been moved to the right as described, the pistons 4b being raised in response to such movement, and the valve member 2b being lowered also in response to the movement of the rod l4, the part of the mechanism so far described is arrested in that position. The system also comprises a servo-motor consisting of cylinder la having a piston lb movable therein, which is preferably also of the diiferential type. The movements of this piston lb are controlled by a slide valve 8a having a valve member 8b movable therein. A rod [5 connected to the piston lb is movable in unison therewith and to the rod l5 there is connected a bell crank lever 91:. controlling the movements of a linkage system Sb connected to the valve member 8b and operatively connected to a further cam lllb. Cams Illa and lllb are driven by chains or belts lllc and llid from a double sprocket or pulley llle rotated by a gear H1 and worm lflg from a drive motor llli through a variable friction coupling lllh.

The angular relationship of the cams Illa and I b are so timed that when the cam Illa has been rotated to perform the function previously described, the linkage 9b will be actuated by the cam lflb to lower the valve member 8b and open the supply port of the slide valve 8a and deliver fluid under pressure to the left side of the cylinder la thereby actuating the piston lb and rod IE to the right. Movement of the rod IE to the right will rotate the bell crank lever 9a in a clock-wise direction and raise the valve member 8b to close the supply port and interrupt the delivery of fluid to the left side of the cylinder la.

A series of conveyor members or elements ll previously described as traveling beams are supported on the heads of the pistons 4b by means of rollers l8, and movement of the rod l from the left to the right will propel the conveyors from the position of the rollers shown in full lines to the position shown in broken lines.

The pump [3 continuously driven by the motor llli draws fluid from a sump I? to deliver it under pressure through a supply conduit system 16a to the right side of the cylinders la and la and to the slide valves 2a, 5a and 8a. A return or discharge conduit system lfib is connected to each of the slide valves 2a, 5a and 8a and to the cylinders 411 for returning fluid therefrom to the sump. The supply conduit system lBa may be provided with an automatic or manually operated relief valve IQ for by-passing the drive system and returning the fluid to the sump.

When the system has been actuated to the positions where the cams lfla and lllb have been rotated 180, namely to the position where all the pistons 4b are raised and the traveling beam ll has been moved to the right, further rotation of the cam Illa and lllb will actuate the mechanism for a return stroke. The diagram l2 in Figure 1 shows 4 movements of the traveling beam ll. In the position illustrated in Figure l the traveling beam is at the point A of the diagram and the actuation of the servo-motor la, lb and of the pistons 41) will bring the traveling beam to the position B. Actuation of the servo-motor la, lb will bring the traveling beam from the position B to the position C.

It will be understood that the cams Illa and lllb may be provided with a, desired number of dwells and rises having a suitable angular relationship to each other and to the dwells or rises of the other cam in order to supply and discharge pressurized fluid to and from the slide valves 2a, 5a and 8a, and thereby to the cylinders la, 4 and la in any desired sequence. After each actuation of the pistons lb and 4b there is a period of rest during which the piston 7b is actuated and thus the diagram l2 may be completed by a downward stroke of the pistons 4b corresponding to movement between the points C and D and a return horizontal stroke of the rod l5 corresponding to movement between the points D and A. During such return strokes, the left hand sides of the cylinders la and la and the lower end of the cylinder 4 are placed in communication through their respective slide valves with the discharge or return conduit system llib so that the fluid under pressure continuously supplied to the right side of each of the cylinders la and la will return the pistons lb and lb to the positions shown in Figure 1.

In Figure 2 there is shown a traveling beam 2! between two fixed parallel guides 22. The traveling beam is in its position of rest corresponding to the point A and the sequence of operation will first raise it and then move it in the direction of the arrow. In Figure 3 there are shown two traveling beams 23 with intervening fixed guides 24 from which they will first be raised by a common piston 4b and then propelled in the direction of the arrows.

In Figure 4 there are shown paired traveling beams 25 in the position corresponding to point A and paired traveling beams 26 in the position corresponding to point D, with intervening fixed guides 26. The traveling beams 25 will move in one direction while the beams 26 move in the opposite direction.

Figure 5 indicatesthat a traveling beam 28 of curved shape may be positioned between two curved guides 29 instead of in the rectiliner form illustrated in Figure 2-4. It will be understood that a drive system as illustrated in Figures 3, 1a and lb is provided in parallel relationship for each of a plurality of parallel beams 2l as illustrated in Figure 2 or for each pair of traveling beams 23 illustrated in Figure 3 or 25 on the one hand and 26 on the other hand illustrated in Figures 3 and 4. For each such drive system it will be necessary to provide only a part of the drive system namely a servo-motor la, lb with control valve 211 and cam Illa, a series of lifting motors 4 with control valve 5b and actuating rod 14 and a servo-motor la, lb with control valve Ba and cam lllb. The same driven motor I62 and pump l3 may supply the motive power to all of the cams Illa, llib and respectively the hydraulic power to all of the servo-motor and lifting motors.

Having now particularly described and ascertained the nature of my said invention, and in what manner the same is to be performed, I declare that what I claim is:

1. A device for causing advancement of objects in a tunnel kiln, comprising a plurality of elements each of which is supported in a horizontally slidable relation by a plurality of first pistons contained in cylinders, and is connected to a further piston in a further cylinder actuating a horizontal displacement of said element, pipes for feeding a pressurized liquid to and discharging said liquid from both ends of said cylinders, valves controlling the flow of said liquid to and from the ends of said cylinders, levers one point of each of which is connected to one of these valves for controlling the position of the latter, another point is operatively connected to the corresponding first piston, and a control mechanism connected to a third point of each of said levers for displacing the same successively and alternately in the opposite directions.

2. A device as claimed in claim 1, in which the said control mechanism comprises a rod for displacing simultaneously all the third points of the levers connected to the first mentioned supporting pistons, a further piston operating in a further cylinder for moving said rod, pipes for feeding a pressurized liquid to and discharging it from both ends of the last said cylinder, a, valve controlling the flow of said liquid to and from the ends of the last said cylinder and a lever one point of which is connected to this last mentioned valve for controlling the position thereof, another point is operatively connected to the last said piston, and .a third point is operatively connected to said control mechanism.

GIAN GIACOMO DRAGO.

No references cited. 

